This invention relates to electrochemical cells which are used as battery power sources by converting chemical energy to electrical energy. More particularly, this invention relates to batteries which accomplish the conversion of chemical energy to electrical energy by using a solid state electrolyte in which protons are mobile.
Batteries have been developed which contain a solid rather than liquid electrolyte, since these exhibit practical advantages such as a high form factor, thin, flat, flexible shapes and avoidance of fluid leakage or drying out. However, such batteries generally employ electrodes composed of metals, such as palladium (see for example U.S. Pat. No. 4,894,301), which are expensive or materials which may be dangerous to health and difficult to manufacture.
In the past, aromatic nitro compounds were considered for active battery cathode materials in non-rechargeable batteries and only for liquid aqueous electrolytes (see for instance U.S. Pat. 2,306,927, Dec. 29, 1942, U.S. Pat. No. 3,025,336, Mar. 13, 1962, R. Glicksman and C. K. Morehouse, J. Electrochem. Soc., 105 (1958) 299 and R. Udhayan and D. P. Bhatt, J. Electrochem. Soc., 140 (1993) L58). Since these compounds are reduced irreversibly under these conditions, they are not suitable for rechargeable batteries. In addition, these compounds suffer from one or more of the following deficiencies: low cell voltages, toxic, significant solubility in the electrolyte, instability with regards to the electrolyte, poor shelf-life, high self-discharge, and low power density.
Further prior art considered the halogenated organic compounds for active battery cathode :materials because of their generally higher voltage but only in non-rechargeable batteries and only for liquid aqueous electrolytes (U.S. Pat. No. 2,874,079, Feb. 17, 1959 and R. Udhayan and D. P. Bhatt, J. Electrochem. Soc., 140 (1993) L58). Besides the disadvantages mentioned above for the aromatic nitro compounds, the halogenated compounds also suffer from being corrosive, give chlorine odors and are difficult to handle. In still more recent prior art, some aromatic quinone compounds have been used as anodes in liquid aqueous electrolyte batteries (see for instance H. Alt, et. al., Electrochim. Acta, 17 (1972) 873 and F. Beck, et. al., The Electrochemical Society Abstracts, No. 152, October 1994 Meeting). However inherent deficiencies limit their applicability in practical batteries. These electrode materials are not stable with respect to the liquid electrolyte and so they degrade. In addition, these electrode materials are soluble in liquid electrolytes and so the integrity of the electrodes is significantly diminished and there is high self-discharge and poor shelf life. Furthermore, they are not useful in practical batteries because their voltages are generally too low.